1. Field of the Invention
The present invention relates to a piezoelectric device and a method for using the same, and in particular, relates to a structure of a device using a piezoelectric element which operates by use of a piezoelectric effect or inverse piezoelectric effect of a piezoelectric body film such as a piezoelectric actuator, an acceleration sensor, and an angular velocity sensor and to a method for maintaining an operation performance of the piezoelectric device.
2. Description of the Related Art
A piezoelectric actuator and piezoelectric sensor using a piezoelectric body film made of lead zirconate titanate (PZT) or the like have been widely known. A PZT film of related art has needed to undergo a polarization treatment in a manufacturing process of a device for obtaining a predetermined piezoelectric performance. Japanese Patent Application Laid-Open No. 4-082309 (PTL 1) discloses that heating (aging) is performed in a manufacturing stage of piezoelectric components to polarize a piezoelectric body used for the piezoelectric components to be subjected to a treatment with an applied voltage of two to two and a half times that of a coercive electric field (claim 1 in PTL 1). PTL 1 also describes that the applied voltage equal to or more than three times that of the coercive electric field is needed in general as a condition for the polarization treatment of a piezoelectric material (on the right-hand section in page 1 of PTL 1).
Japanese Patent Application Laid-Open No. 2007-040879 (PTL 2) describes a method for polarizing a vibrator for piezoelectric vibrating gyro. PTL 2 proposes that a high electric field is applied between electrodes to treat polarization in the air (claims 2 and 3 in PTL 2).
Japanese Patent Application Laid-Open No. 2005-340631 (PTL 3) describes that piezoelectric element components are treated with polarization at a temperature higher than a reflow temperature (claim 1 in PTL 3).
Japanese Patent Application Laid-Open No. 2011-078203 (PTL 4) proposes a piezoelectric actuator using a piezoelectric body film which has polarization characteristics of an asymmetric bipolar polarization-electric field curve (Pr-E hysteresis) and a driving method thereof.